Coherent ratchets in driven Bose-Einstein condensates.
نویسندگان
چکیده
We study the response of a Bose-Einstein condensate to an unbiased periodic driving potential. By controlling the space and time symmetries of the driving we show how a directed current can be induced, producing a coherent quantum ratchet. Weak driving induces a regular behavior, and space and time symmetries must both be broken to produce a current. For strong driving, the behavior becomes chaotic and the resulting effective irreversibility means that it is unnecessary to explicitly break time symmetry. Spatial asymmetry alone is then sufficient to produce the ratchet effect, even in the absence of interactions, and although the system remains completely coherent.
منابع مشابه
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Cold atom devices permit the exploration of novel forms of quantum transport that are difficult or impossible to realize in traditional electron transport setups. Under the action of an external driving, long-term coherent atom motion can be quite sensitive to the initial switching conditions even in the presence of interactions [1]. If the driving violates spaceand time-inversion symmetry simu...
متن کاملComment on "Coherent ratchets in driven Bose-Einstein condensates".
Creffield and Sols (henceforth CS) [1] recently reported a finite, directed time-averaged ratchet current, for noninteracting quantum particles in a potential Vðx; tÞ 1⁄4 KVðxÞfðtÞ with time-periodic driving fðtÞ 1⁄4 fðtþ TÞ, even when time-reversal symmetry holds, as depicted with the solid line in Fig. 3 in [1]. CS chose VðxÞ 1⁄4 sinðxÞ þ sinð2xÞ, fðtÞ 1⁄4 sinðtÞ þ sinð2tÞ ( 1⁄4 0 in their Fi...
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ورودعنوان ژورنال:
- Physical review letters
دوره 103 20 شماره
صفحات -
تاریخ انتشار 2009